I am using ECharts for creating a live ECG Monitor. I started with dynamic data example, https://echarts.apache.org/examples/en/editor.html?c=dynamic-data2
and modified the data to simulate ECG data.
How I rendered ECG data?
I used 2 line series and filled data from a ECG data array. Basically splitting the ECG data to 2 sub arrays.
var EcgData=[ 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];
var splitPointer = 0;
const EraseWindow = 200;
var counter = 0;
function randomData() {
value = EcgData[counter%EcgData.length];
counter++;
return {
name: counter%EcgData.length,
value: [
counter%EcgData.length,
Math.round(value)
]
};
}
var data = [];
for (var i = 0; i < EcgData.length; i++) {
data.push(randomData());
}
option = {
title: {
text: '???? + ?????'
},
xAxis: {
type: 'value',
splitLine: {
show: false
}
},
yAxis: {
type: 'value',
boundaryGap: [0, '100%'],
splitLine: {
show: false
}
},
series: [{
name: '????',
type: 'line',
showSymbol: false,
hoverAnimation: false,
data: data
},
{
name: '????',
type: 'line',
showSymbol: false,
hoverAnimation: false,
data: data
}]
};
function arrayRotate(arr, reverse) {
if (reverse) arr.unshift(arr.pop());
else arr.push(arr.shift());
return arr;
}
setInterval(function () {
splitPointer = data.length - counter % data.length;
splitPointer = data.length - splitPointer;
var p1 = data.slice(0, splitPointer);
var p2 = data.slice(splitPointer + EraseWindow);
p2.pop();
counter++;
myChart.setOption({
series: [{
data: p1
},
{
data: p2
}]
});
}, 1);
As you could see each time triggering setOption with full data (shifted) and rendering it.
myChart.setOption({
series: [{
data: p1
},
{
data: p2
}]
});
But when I tried to add 4 such ECG Views I started getting slow rendering and low FPS and many frames missed rendering.
But in an ECG data, we just need to render latest data received after clearing a rectangular portion.
Do we have an option to set only updated portion of the series data?
Meanwhile I saw EChartsGL (https://github.com/ecomfe/echarts-gl) for WebGL rendering. Is it possible to use echarts-gl for for real-time plotting of 2D points (ECG data)? Any example of using echarts-gl for 2D line rendering will help.
Try rendering graphics with Canvas. In theory it should give you better perfomance results.
const chart = echarts.init(dom, null, {renderer: 'canvas'});